During the third week of August, the biggest weekly gainers in the NRN Social 200 index improved their scores off of relatively healthy bases, including a double-digit gain for casual-dining powerhouse Red Lobster.

For Bob Evans, Buca di Beppo and Red Lobster, which placed first, second and third, respectively, among the largest growth in index scores from Aug. 10-16, special offers drove the most interest on the brands’ social media platforms. As restaurants have shown several times this summer, contests and sweepstakes are reliable ways to get fans liking a brand page or an individual Facebook post, and family-dining brand Bob Evans led the way using that tactic.

Red Lobster announced the return of its Endless Shrimp promotion during the week to a major outpouring of excitement and support on its Facebook page, accounting for a 12.3-percent gain off of an already high base score in the 40s.

Another chain with a large social following, Chick-fil-A, also moved the needle last week, not by making an aggressive offer but by starting a spirited debate among its fans over pickles.

1. Bob EvansWeekly percent change: +26.8%Index score: 18.10

The family-dining chain typically elicits a few hundred likes and a few dozen shares with its normal Facebook posts, which usually advertise menu items with professional food shots. But several times in the past few weeks, including a post on Aug. 15, Bob Evans has driven a spike in Facebook engagement with a post about its sweepstakes for a $25 gift card each week, with a grand prize of a $100 gift card at the end of the contest on Aug. 21. Facebook users need only like Bob Evans’ page to enter. The chain’s last sweepstakes post received more than 5,800 likes, 200 shares and 300 comments.

2. Buca di BeppoWeekly percent change: +22.9%Index score: 24.24

Buca di Beppo’s promotional strategy on Facebook relies heavily on discounts and offers, including its current “4 Eat for $40” and a previous buy-one-get-one for National Lasagna Day. However, during the third week of August, Buca inspired outsize engagement with a Facebook offer for $15 off a bill. More than 77,000 people claimed the offer and another 18,700-plus people liked the post that delivered it. The post also received nearly 2,400 shares and more than 1,200 comments. In July, Buca drove similar spikes in likes, comments and shares with a Facebook offer.

3. Red LobsterWeekly percent change: +12.3%Index score: 47.96

Casual-dining giant Red Lobster was one of the few major chains this summer to spur a double-digit gain in its NRN Social 200 index score off a base higher than 40, and during the third week of August, that increase clearly came from the brand’s promotion of its popular annual Endless Shrimp promotion. Its Facebook post Aug. 12 announcing the return of Endless Shrimp received nearly 152,000 likes, one of the only six-digit totals for likes seen thus far in NRN’s tracking of social-media content for the Social 200’s top weekly gainers. The post also received more than 26,000 shares and more than 6,000 comments. A similar tweet with the same picture was retweeted more than 1,300 times and favored more than 400 times.

While nearly 30 points of Chick-fil-A’s Social 200 index value of 44.62 come from its Facebook component, the brand’s Twitter component contributes about another 12 points, making Chick-fil-A the most active brand on Twitter among the third week of August’s top gainers. The brand’s tweets largely mirror the content of its Facebook posts and routinely inspire dozens of retweets, favorites and responses, though there was no discernable spike in engagement for any one tweet during the week.

On Facebook, however, Chick-fil-A received several times its typical volume of likes, comments and shares for an Aug. 14 post asking, “Which side are you on: pickles or no pickles?”

5. Noodles & CompanyWeekly percent change: +9.5%Index score: 11.25

Fast-casual chain Noodles & Company’s Social 200 index score gets more of an even spread among the three major platforms, with Facebook contributing 5.56 points, followed by YouTube with 3.05 points and Twitter with 2.64 points. The brand’s high volume of posts on Twitter mostly involve responding to customer complaints or questions, and Noodles’ last YouTube post was a video from NRN’s MenuMasters Awards celebration posted in June.

The brand posts several kinds of content on Facebook, from slick food shots to fan-submitted photos. Noodles’ most-engaging Facebook post of the week was a picture of a billboard from its new branding campaign launched this year, and the post received nearly 650 likes.